Randomized controlled trial of vitamin D supplement on endothelial function in patients with type 2 diabetes - Yiu, Y F; Yiu, K H; Siu, C W; Chan, Y H; Li, S W; Wong, L Y; Lee, S W; Tam, S; Wong, E W; Lau, C P; Cheung, B M; Tse, H F (Atherosclerosis, 2013)